Audio system



FIG. 1 is a perspective view of an audio system, embodying our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof.

The broken lines shown are included for the purpose of illustrating the unclaimed portions of the audio system and form no part of the claim. 

The ornamental design for an audio system, as shown and described. 